Dengue is an acute viral disease of man which is transmitted by mosquitos. It is endemic in the tropics and subtropics, worldwide, where an estimated 100,000,000 cases occur annually Although relatively rare, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) are significant causes of death in children. At present, there is no vaccine to protect against dengue and attempts to prevent disease by controlling the mosquito vector have proven largely ineffective. Thus, there remains a need for a safe and effective vaccine to protect against disease caused by dengue virus.